This invention relates to a resonant vibrating power toothbrush having first and second vibrating members joined by a hinge portion and a spring and driven by an actuating member, and also concerns a power toothbrush having a brushing pressure feedback capability.
A wide variety of power toothbrushes, using various driving arrangements, are well known. Power toothbrushes generally provide a better and more reliable cleaning action than manual toothbrushes and accordingly are generally preferable in order to maintain good dental hygiene. Many of these toothbrushes are powered by a self-contained DC battery. The driving arrangements include various motors which produce a variety of brushhead motions, including rotary and back-and-forth actions, as well as other arrangements using magnetic drivers.
The frequency of the brushhead action of these toothbrushes varies considerably, typically from a few Hertz to several thousand Hertz and, in some cases, ultrasonic frequencies. Many of these power toothbrushes, however, are expensive and at least in some cases are quite complex in design and operation. The expense and complexity of such power toothbrushes preclude a particular class of customers from receiving the cleaning benefits of a reliable power toothbrush. Hence, it would be desirable to have a power toothbrush which has a frequency and amplitude of motion which is effective in cleaning teeth, but is also inexpensive to produce and reliable in operation.
One important operational feature of a power toothbrush is the brushing pressure applied to the teeth. Proper brushing pressure has been discovered to be important in terms of achieving a desired cleansing effect, but care must be taken to not apply too much pressure, which may damage gums and other tissue or too little pressure, which would not be effective in cleaning. Numerous attempts have been made to produce accurate brushing pressure information with an indicator which can readily communicate to the user that the brushing pressure is either within a desired range or too high or too low. However, the known brushing pressure indicator systems are often quite complex, expensive and unreliable. Hence, it would also be desirable to have a reliable and inexpensive brushing pressure indicator for a power toothbrush.
A first aspect of the present invention is a vibrating toothbrush which has a handle portion, comprising: a first vibrating arm portion, having a brushhead mounted at a free end portion thereof; a second vibrating arm portion, connected to an opposing end of the first arm portion by a hinge acting connecting element, wherein the first and second arm portions have first and second natural resonant frequencies; a spring member connecting the second arm portion in the vicinity of a free end thereof to the first arm portion; an actuator connected between the first and second arm portions; and a switch element for selectively applying a DC voltage to the actuator, wherein in operation, when the switch is closed, the first arm portion is drawn toward the second arm portion by the actuator, which compresses the spring element and opens the switch element, and wherein return action of the spring when the switch element is open moves the first arm portion away from the second arm portion to the point where the switch again closes, resulting in a back-and-forth movement of the brushhead.
A second aspect of the invention is a vibrating toothbrush which includes a pressure feedback capability, comprising: an arm portion on which is mounted a brushhead at a free end thereof; a driving assembly for moving the arm portion and hence the brushhead in a manner to clean teeth; a spring element connected between the driver assembly and the arm portion; and a nodal mount connecting the spring element to the handle at a preselected position therealong, wherein the preselected position is such that when the brushhead is loaded with a preselected correct amount of brushing pressure, vibration to the handle through the nodal mount is significantly reduced, indicating to the user that a correct brushing pressure is being used.